The statements in this section merely provide background information related to the present disclosure and may not constitute prior art.
DE 100 40 711 A1 discloses a vane cell pump with a ring-shaped inner rotor in which a plurality of vane elements extending radially outward is housed in a radially displaceable manner. The radially inner end areas of the vane elements abut a non-rotatable central part, while the radially outer lying end areas abut a non-rotatable outer ring. The rotor can be turned on a rotational axis that is offset from the center axis of the central part and the outer ring. As a result, feed cells of initially increasing volume followed by those of decreasing volume form between the vane elements when the rotor is rotated. The volume change of the feed cells causes fluid to be first suctioned into the feed cells and then discharged back out. The end areas of the vane elements glide on either the central part or the outer ring according to their positions. A vane cell pump of this type can be manufactured easily and economically.
For the purpose of increased efficiency, DE 195 32 703 C1 discloses a vane cell pump in the form of a reciprocating vacuum pump. In this pump, the vane elements are displaceably housed in an inner rotor, while at the same time they are pivotably held in a ring-shaped external rotor. The rotational axis of the inner rotor is offset from the rotational axis of the external rotor; this results in feed cells initially increasing in volume and then decreasing in volume as described previously. The reciprocating vacuum pump described in DE 195 32 703 C1, however, is complex and therefore expensive to manufacture.